Reading gzip files in Python 2.6 not supported

xray/core/dataset.py

@@ -2,6 +2,7 @@
 import functools
 from io import BytesIO
 import warnings
+import sys
 
 import numpy as np
 import pandas as pd
@@ -64,6 +65,8 @@ def open_dataset(nc, decode_cf=True, mask_and_scale=True, decode_times=True,
         if nc.endswith('.gz'):
            # the name ends with .gz, then gunzip and open as netcdf file
            # FIXME: does ScipyDataStore handle NetCDF4 files?
+           if sys.version_info[:2] < (2, 7):
+              raise ValueError('reading a gzipped netCDF not supported on Python 2.6')
            store = backends.ScipyDataStore(gzip.open(nc), *args, **kwargs)
         elif not nc.startswith('CDF'):
            # it does not appear to be the contents of a netcdf file we load

xray/test/test_backends.py

@@ -7,6 +7,7 @@
 import os.path
 import tempfile
 import unittest
+import sys
 
 import numpy as np
 import pandas as pd
@@ -175,9 +176,13 @@ def test_roundtrip_example_1_netcdf(self):
                 self.assertDatasetIdentical(expected, actual)
 
     def test_roundtrip_example_1_netcdf_gz(self):
-        with open_example_dataset('example_1.nc.gz') as expected:
-            with open_example_dataset('example_1.nc') as actual:
-                self.assertDatasetIdentical(expected, actual)
+        if sys.version_info[:2] < (2, 7):
+           with self.assertRaisesRegexp(ValueError, 'gzipped netCDF not supported'):
+                open_example_dataset('example_1.nc.gz')
+        else:
+           with open_example_dataset('example_1.nc.gz') as expected:
+                with open_example_dataset('example_1.nc') as actual:
+                    self.assertDatasetIdentical(expected, actual)
 
     def test_orthogonal_indexing(self):
         in_memory = create_test_data()